Preparation of organic esters



2,663,120 rnsmnnrois; 9F OBQAHIC; 13515.55

Eugene mu, Detroit, Mieln, assigpor to Eth r flnrporatijo lflm York, Y1;a'eorporationof- Delaware;

mowing egplipationsentemher 285 15 .51. sierjal'No- 241L5i 5 Claims.

Y M} I v This; airentiohe perta ns to the-preparations. of esters,ands-mo e part oularlsto anemprosssst n makinsesterslof metalsoigmup Illfirott e pe iodict bla;

- ar ous stersot these. metals: have been Pre- Qarsde Two: me hods; aregener lly emnloyed.

Qne nmlves cqndensatioa of lm-alcohol and; a

metal tetrahalide like iQh in the PIGSQQQG of metal c/mammalscondensingeent; The .chemiealabeh v or ot the g up 18/? B3 elements,

esgesial s titanium andrz monium, is suc that, ylthonsh; they have a,valence. one, aleoholt W111 ene a ly r place my three-0 thehal gen sutitueots hefoorth hal es :lsso closelabound taithametaltthat a stro g:condens n asent is ed to effect its-removal. and a ow addit on otthurthtalcohol,sm g.

The eeondlmethod art eu arls useful:- for th hi h,halooholsandoonseemntl thezmoracom glea -esters -ls aster w th hedesiredalcoh l, ormi-na the n w nr duotvb trens sterifi ation, This methorzlr vi liouslaroquir stthe previous-immanent by her means of the metal esterstarting reactant so -.thatthe first; nrooedunea oxe, desoribed is thasic, one, Thatr-oropeduneehowever, has ne sxayedisadv ntase:in.-thatwetsuit-sodium i wa highly expensive material.

It has now been-discovered that tetraesters of thesea mup ll/i' lmetals; oanzreadily' hentena d be .eansof erase SQ -Qhi 'Q mush moroefie tivethaas d mwanlclryet-are rnateriale can be condensedwithtitanium tetrachloride or i er: a osleiumwozzabarinz-n or:

to reset relatitlelyzsimpl metal atoms-are removed from the B1 metalandreplaced by 'alkoxy groups. Such products as tetraeth-yltitanate,tetrabutyltitanates, tetra'pror pylzirconates; etc. are'recovered, Theseare recognized as of" great utility incommerce, partieularl'y asWater-proofing agents for; fabrics and textiles.

It ispossi-ble toefiect the "reaction by simultaneously commingling thealcohol, halide and mixed-metals condensing agent: I;t -is also*-per*feotly feasible toreact the a-loohol first with-the condensing agent andthenintroducethe B metal halide; However -in commercial operationforbest results and highest yields,it-isverydesirable to condense thehalide with the algoholiji e. so that as-ma-nyalcohol groups aspossibleywill be added tothe metal-atom; and then to react thecondensate-with the mixture'of alkali metal andalkaline earthmetal. Forinstance," when an alcohol (ROB?) is treated with titanium-tetrachloride, presumably an intermediate like TiKDRMCL-tHCl isvformed'a Thecondensing agentthen serves bothto remove the last chlorine: atom and tocom-Q- bine with thetthree moleoules of" HGI'. The alkali;metale'alkali-ne earth metal agent is: for some reason much more potentthan alkalrmetat alone imefiecting this removal and combination.

one methodzof operating this invention; is espeqialiyi successfult andpreferred; because it utilizesva relatively cheapbyv-product;which-would otherwise he of little or no valueand extremelydiffloflltr'toidisposeqofl' This preferred procedure isvto condehse thealcohol and the tetrahalide with sludge-residue fromanhydrousalkalimetal halide-electrolysis; j

Alkali metals are generally" prepared by" elec trolyzinga fused alkalimetal halide eta-comparatively high temperature. An alkaline earthhalldeis usuallyadded to the melt to lower its meltingflpoint.The-desiredalkali metal is separated} fromthe -mass aftereleotrolyzing;but a heel on residue of so-called sludge-" remains.

, Thiaconsistsotthe-added alkaline earth metal andaalkali metal whichhas not easily-separated;

together withlpossibloother contaminants; This metali production may becorrespondingly 1 rea duceci-ssometimes-.thetsludgeeiswfllteredirwhereby The sodium-calcium mixture iscooled to about.

150 C. to precipitate the latter metal. The supernatant liquid sodium isthen decanted, leaving a sludge residue composedof about 70% sodium,

120% calcium and 10% metal oxides and chlorides.

'If the sludge is then filtered again, the filtercake still containsabout 40% sodium, 40% calcium and of other contaminants. Sometimespotassium chloride is introduced to the electroliysis as well as calciumchloride, hence potassium may be one of the contaminants. Depending up--on the particular conditions of electrolysis and the extent to whichthe residue is further treated to recover sodium values, the finalsludge (either the cell residue as such or the refiltered filtercake)may contain anywhere from to 95% by weight of sodium and from 5% to 75%by Weight of calcium. 1

As previously indicated, it is such sludge resi* dues which areparticularly successful as condensing agents in the present process. Avaluable use for these hitherto undesirable and hazardous materials hasbeen discovered. Furthermore, the-process in which they are used is anincomparable improvement over that previously known.

The different operating conditions for the present invention willobviously vary interdependently with one another. Thus, the reactiontemperature should be correlated with the particular halide and theparticular alcohol employed. The temperature is generally maintained atsomewhat below the boiling point of the halide until condensation issufliciently complete to avoid loss of this reactant. Thereafter, thereaction. can

proceed simply at room temperature, or prefer- ,4

ably at a temperature about as high as the normal reflux temperature ofthe alcohol. Preferred alcohols are those of the monohydroxy aliphaticseries containing between one and eighteen carbon atoms. It is oftenbetter, also, to

maintain an excess of alcohol during the operation, or in the case of atetrahalide more than four moles of alcohol per mole of halide. Thereaction is generally conducted in a suitable solvent. This solvent canvery'well be the excess residues can be used in bulk, i. e. in largepieces as they are obtained from the cell or second filtercake;.-Preferably, however, for greatest reactivity they are utilized-indispersed form. To prepare such dispersions, the residue is remelted toa temperature of about the melting point of the alkali metal componentin the presence of an inert diluent, preferably a hydrocarbon, asurface-active agent is then added, and the mass is allowed to solidifyin that dispersed condition. As is obvious from the above discussion ofthe type of reaction which apparently occurs, it is best to use aboutiourequivalentsof condensing agent for the amount of halogen bound tothe group IV 13 metal. Similarly, for complete reaction about four molesof alcohol should be used for each mole of group IV B metal tetrahalide.

The following examples are given by way of illustration and are not tobe considered as the only embodiments of this invention. It is to beunderstood that protection hereof is only to be limited by the specificwording of the appended claims.

Example I A solution of 300 parts of dried secondary butyl alcohol wasprepared in 250 partsof dried benzene and cooled to 8 C. 96.4 parts oftitanium tetrachloride was added to the mixture during a period ofone-half hour, while the temperature was maintained at between 5 and 10C. The reaction mass was then stirred at a temperature of 10 C. for onehour and at a temperature of 25 C. for an additional five-hour period,and then warmed to reflux. Filter sludge was recovered from a sodiumcell, analyzed and found to contain about active sodium and 'calciummetals, 70% being sodium and 20% calcium. This sludge was added in smallpieces tothe chloride-alcohol reaction mixture, until 56.3 parts hadbeen introduced. The benzene solvent was removed by distillation at apot temperature of about C. and the residue was distilled at reducedpressure. A colorless, somewhat viscous oil resulted, boiling point at 1mm., l20-l25-C. and 12 l.45l5-1.4545. The product comprised thetetra-sec-butyl ester of titanium in a yield of 81.6%, based on theinitial TiCli. Based on the sodium content of the sludge, the yield was96.8%.

The above process was repeated, but pure so:- duim was substituted forthe filtercake. Ayield of only 28.4%, based on the TiCh, was obtained.

Example II Tetraethyltitanate was prepared by'mixing942 parts of TiCliwith 804 parts of dried ethanol. Sodium-calcium filtercake, containing50% cal: cium, 40% sodium and 10% oicontaminants including potassium wasmelted, treated with a dispersing agent and allowed to solidify. Thismaterial was then added in small bits to the chloride-alcohol reactionmixture, 57 parts by weight in all being used. The mass was stirred at18 C. for 1%; hours, at room temperature for an additional hour andunder refluxing conditions for three hours. The excess alcohol solventwas removed by distillation ,and the residue further distilled atreduced pressure. A high yield of the tetraethyl ester of titaniumresulted.

- Itwas a dark yellow viscous oil: B. P. at 1-4 min,

122-145 C.; 11. 1.4845-1.50l8. Tetraethyl zirconate was readily preparedby this same procedure, using ZrCh.

Ewample III Tetraisopropyltitanate was prepared by' reactin'g one-halfmole of titaniun 'tetrachlorid with four moles of 'isopropyl alcohol inthe presence of four equivalents of a condensing agent con sisting of'75 sodium and 25% calcium.

The same ester resulted when titanium tetrabromide was substituted forthe TiCh and the condensing agent comprised 75% by weight of potassiumand 25% by weight of barium.

I claim:

1. A process which comprises interreacting an alcohol, a halide of aperiodic group IV B metal and. a mixture containing an alkali metal andat least 5% by weight of an alkaline earth metal.

2. A process which comprises condensing an aliphatic alcohol with atetrahalide of a periodic group IV B metal and reacting the condensatewith a mixture of an alkali metal and an alkaline earth metal, saidmixture containing at least 5% by weight of said alkaline earth metal.

3. A process according to claim 2 wherein the tetrahalide is titaniumtetrachloride.

References Cited in the file of this patent Speer, J. Org. Chem vol. 14,pages 655-59 (1949). v

1. A PROCESS WHICH COMPRISES INTERRRACTING AN ALCOHOL, A HALIDE OF APERIODIC GROUP IV B METAL AND A MIXTURE CONTAINING AN ALKALI METAL ANDAT LEAST 5% BY WEIGHT OF AN ALKALINE EARTH METAL.